Thick black layer under flooring

[Jmchattie]

Hello - I bet somebody knows this in 3 seconds, but I don't so hopefully you can help.

I've removed a cupboard from a room with a vinyl floor and there's no floor covering in the gap. What is there is a thick (15mm) black hard covering which is broken near the edges, perhaps from old carpet grippers being nailed down.

Any idea what it is? And do I need to repair it before putting underlay and carpet over the top?

I'll attach a couple of photos if it works.

Thanks all.

 

[mark_elliot]

look like asbestos tiles...but I'm not sure.But if so, it’s better to take them off

 

[James Henry]

Yeah, you are right. Anybody can understand and know it in 3 seconds.
I see your uploaded pics and you must repair it before putting....

 

[Doghouse Riley]

Yeah, you are right. Anybody can understand and know it in 3 seconds.
I see your uploaded pics and you must repair it before putting....

That's not always true.
There are generations who are good at DIY. Either a real interest or because of an economic necessity in their youth, which may become an interest. as in my case.
There are generations, of which some wouldn't know how to wire a plug, or make a straight cut with a hand saw.
Because previously, they've never had to.